(1) Field of the Invention
The present invention relates to slide assemblies using ceramic members.
(2) Related Art Statement
Since slide members, particularly, slide members used in engines and the like are heated at high temperatures and must withstand friction under high speed rotation, metallic materials which withstand high temperatures, for instance, heat resisting alloys, and the like, have formerly been used by employing a liquid lubricant such as oil as an intermediate.
However, use conditions required for the slide members have been getting severer year by year, and there is a demand for operating such slide members without using a liquid lubricant. Metallic materials have a defect that they can not withstand use temperatures or friction or they must be replaced after a short cycle.
Under the circumstances, it has been considered that ceramic materials are used as slide members.
While ceramic materials withstand high temperatures and have high wear resistance, they are unfavorably brittle. However, all ceramic materials cannot be used for this purpose. Coefficients of friction between ceramic materials and metallic materials in a high temperature dry atmosphere are generally in a range of from about 0.5 to about 0.6, which is considerably higher as compared with a coefficient of friction of 0.1 to 0.2 required for slide members used in engines, and the like.
In order to eliminate the above-mentioned problem, NGK Insulators, Ltd. discloses in Japanese patent application Laid-open No. 62-13,820 a slide assembly comprising a ceramic member and a metallic member having a slide surface coated with a mixture of LiF and Cu.
However, although the slide assembly disclosed in Japanese patent application Laid-open No. 62-13,820 can attain excellent sliding performance, its coefficient of friction is around 0.4. Further, a wear amount of a mating member is large during sliding. Thus, such a slide assembly does not afford sufficient sliding performance as in engines or the like.